Regeneration of storage-battery elements



Patented Apr. 1, 1924.

UNITED STATES I 1,488,481 PATENT ounce;

THOMAS A. EDISON, OF LLEWELLYN PARK, WEST ORANGE, NEW JERSEY, ASSIGNOR TO EDISON STORAGE BATTERY COMPANY PORATION OF NEW JERSEY.

, OF WEST ORANGE, NEW JERSEY, A COR N Drawing.

To all whom it may concern:

Be it known that I, THOMAS A. EDISON, a citizen of the United States, and a resident of Llewellyn Park, West Orange, Essex I County, New Jersey, have invented certain form of whichthe-active material of the positive elements comprises nickel hydrate,

usually comprisingseveral difi'erent hydroxides of nickel and the active material of the negative elements com rises electrolytically active iron or oxides 0 iron.

Edison storage battery cells as usuall constructed comprise alternately arrange ositive and negative plates separated an insulated from each other, each of the plates comprising a steel grid carrying a lurality of perforated pockets or tubes with t e active material tight y packed therein. In the case of the posltive plates, the erforated tubes contain alternate layers, 0 hydroxides of nickel as the active material, and metallic nickel flake, the layers of nickel flake merely I serving as conductors between the adjacent layers of the active material. In new. cells prior to the first chargin this active material consists of nickel hydroxide in the lowest or first stage of oxidation, that is, in the nickelous state. Upon charging such cells, this nickelous hydroxide first goes to another and higher state of oxidation andfinally to a still higher state of oxidation,

being then in the form of hydrated peroxides of nickel, or what may be termed the nickelic state. On discharging the cells, however, the active material of the positive elements never returns to the lowest or first stage of oxidation or to the nickelous state, but is merely reduced from higher to lower hydroxides. The .active material of the ositive elements of an Edison cell is the epolarizing material, and when such a cell is charged the active material of the negative elements is changed to metallic iron, while upon discharging of the cell this iron is oxidized.

Application filed April 26, 1922. Serial No. 556,759.

When an Edison cell has been in operation -for a; vvery lon period, however, it is frequently found t at the active material of the positive electrode elements will no longer act as an eflicient depolarizer for the active material of the negative electrode elements. This condition is due in a large measure'to the fact that impurities and foreign matter gradually accumulate on andin the positive elements, and eventually the tubes carrying the active material, and also the active material and the layers of metallic flake nickel disposed between the layers of'such active material, becor -e coated with a scale or crust which seriously impairs the eflicient operation of the cell; In this connection it may be noted that when the layers of metallic flake nickel become thus coated, they will no longer act as eflicient conductors between the super osed layers of the nickel hydrate. The loss 0 efliciency thus caused is especially pronounced in the case of cells not properly cared for, as where distilled water has not been used in replenishin Moreover, in the continue use of an Edison cell a small amount of the electrolytically active iron and iron oxide of the negative electrode elements is gradually carried from the latter by the electrolyte and slowly deposited on and in the ositive elements, which also results in impairing the efliciency of the cell. In my copending application, Serial No. 503,970, filed Sept. 28, 1921,.1 have described the electrolyte.

aprocess for regenerating the nickel hydrate and nickel flake of the positive electrode elements of Edison storage battery cells without removing these materials from the perforated pockets or tubes. However, where the capacity of Edison storage battery cells has fallen to a very low point and where the material in the tubes or pockets of the ositive elements of such cells has been ried and has caked into very hard masses or pencils as, for example, where the elements are scribed herein is an im rovement on that other alkali and may be and preferably is disclosed in such coopen ing ap lication. subjected to the-action of a solution of a In regenerating the layers active -mastrong acid, preferably a 30% solution of terial and nickel flake in the tubes of the hydrochlorine acid, for a short time so as positive elements of Edison storage battery to remove therefrom any remaining im- 70 cells in accordance with the present invenpurities and foreign matter including iron tion, I first split these tubes and remove the and iron oxide, which may have been decaked pencils of active material and nickel posited from the electrolyte of the cell. flake therefrom. These 'caked pencils are The reduced nickel hydrate is then removed then softened sufiicientl to enable the nickel from the. solution of hydrochloric acid, I6 hydrate and the nickel flake tobe readily washed free from such acid by water and separated by washing, the softening prefthen dried at about 212 Fahrenheit after erably being accomplished by subjecting which it'is in a condition to be used over thepencils to the action of a 20% solution again in manufacturin new tubes for the of hyposulphite of soda for a considerable positive elements of E ison storage battery 80- period of time, usually in the neighborhood cells. I of twenty-four hours. The nickel hydrate The nickel flake separated from the nickel is preferably separated from the nickel hydrate as above described, is suitably flake by'washing the same out of the softtreated separately from the nickel hydrate ened pencils through a. screen the holes of so as to remove therefrom iron and other 85 which are much smaller than the nickel incrustations, preferably by immersing the flake, water being used to wash out the nickel same in an approximately 30% solution of hydrate. The nickel hydrate thus sepahydrochloric acid and subjecting it to the rated from the nickel flake is washed free of action thereof for a eriod of about five all hyposulphite of soda and then sub'ected minutes. .The nickel ake is then removed 90 to the action of a slightly alkaline so ution from the hydrochloric acid solution, is of ajsuitable reducing agent. Any of the washed free from hydrochloric acid and .usual reducing agents may be employed dried. The nickel flake thus regenerated is such as glycerine, glucose, a tartrate, or any now ready to be used again with the re-.

sugar, although I prefer to use glycerine generated nickel hydrate or' with other 06 as I find the same to be the most practical nickel hydrate in the nickelous state, in makand efficient material, and that the best reing new tubes for the positive elements of sults are obtained by employing an approxi- Edison storage battery cells. mately 10% solution of glycerine in water While I have described the preferred 36 containing approximately 1% of an alkali manner of carryin out my improved pro- 100 such, for example, as caustic soda. The cess, it is to be un erstood that the-same is alkaline solutionof glycerine is constantly subject to various changes and modifications. maintained at the boiling point and the without departure from the spirit of the nickel hydrate is kept in and subjected to invention and the scope of the appended 40 the action of this boiling solution until .it claims. i I 105- is completely reduced to the n hydroxide, Having now described my invention, what a that is, to nickel hydroxi e in the lowest I claim. as new and desire to protect by 0r first stage of oxidation or the nickelous Letters Patent is as follows: state. I preferably keep the nickel hydrate-- 1. The process which consists in softening in this boiling solution for a period some the mass of nickel hydrate and nickel of a 0 what longer than necessary to reduce all positive element of a storage battery cell the hydrate to the nickelous state, in order of the Edison type, then separating the 7 to remove lime and other com ounds and nickel hydrate from the nickel, and then foreign matter deposited in t e mass of separately regenerating said nickel h drate nickel hydrate from the water added to the and nickel, substantially as describe 11 electrolyte of the cell while the latter was in 2. The process which consists inse service. The reduced nickel hydrate is then rating the nickel hydrate and nickel o a removed from the alkaline solution of positive element of a storage batte cell glycerine or other reducing agent and is of the Edison type, and then separately-re- 5e Washed free from such reducing agent b generating saidnickel hydrate and nickel,

subjecting the same to the action of fres substantially as described. water rendered very slightly alkaline, pref- 3. The process which consists in softening erably to a solution of approximately 13;; the mass of nickel hydrate and nickel of a of 1% of an alkali such as caustic soda. positive element ofa storage battery cell of 60 The nickel hydrate is kept in this solution, the Edison type by subjecting said mass to which is constantly maintained at the boilthe'action of a solution of hyposulphite of ing point, until all the reducing agent is soda, and then separating said nickel hycompletely removed. The nickel hydrate, 'drate and nickel, substantially as described. now in the nickelous state, is then removed 4. The process which consists in softening 65 from the weak solution of caustic soda or the mass of n ckel hydrate and nickel of a positive element of a storage batte positive element of a storage battery cell of the Edison type, and then separatmg said nickel hydrate and nickel by washing the nickel hydrate from the softened mass, substantially asdescribed.

The process which consists in softening the mass of nickel hydrate and nickel of a cell of the Edison type, and then separating said nickel hydrate and nickel by washing the nickel hydrate from the softened mass through a screen the holes in which are smaller than the particles of nickel in said mass, substantially as described.

6. The process which consists in removing from a positive element of a storage battery cell of the Edison type the massof nickel hydrate and flake nickel carried thereby, softening said mass by-subjecting the same to the action of a solution of hyposulghite of soda, and then separating the nickel ydrate and flake nickel by. washing the nickel hydrate from the softened 'mass through a screen the holes in which are smaller than'the nickel flake, substantially as described.

7. The process which consists in separat ing the nickel hydrate and nickel of a positive element of a storage battery cell of the Edison type, and then regenerating said nickel by subjecting the same to the action of an acid substantially as described.

8. The process which consists in separating the nickel hydrate and nickel of a positive element of a storage battery cell of the Edison type, and then regenerating said nickel by subjecting the same to the action of an approximately 30% solution of hydrochloric acid, substantially as described.

9., The process which consists in separating the nickel hydrate and nickel of a positive element of a storage battery cell of the Edison type, and then regenerating said nickel hydrate by successively subjecting,

the same to the action of a solution of a resoda,

Edison type, and then regeneratin ducing agent and to the action of a weak alkaline solution, substantially as described.

10. The process. which consists in softening the mass of nickel hydrate and nickel of a positive element of of the Edison type by subjecting the same to thfi action of a solution of hyposulphite of so a, nickel by washing the nickel hy rate out of the softened mass, washing the nickel hya. storage battery cell-1w separating said nickel h drate and 'drate thus separated free of hyposulphite of and then reducing the nickel hydrate to the first oxidation stage, substantially as' described.

11. The process which consists in separating the nickel hydrate and nickel of a ositive element of a storage battery cell 0 th;

sa1 nickel hydrate by successively subjecting the same to the actions of a reducin agent, g weak'alkaline solution, and an aci substan tially as described.

12. The process which consists in separating the nickel hydrate and nickel of a ositive element of a storage battery cello the Edison type, then subjecting said nickel hydrate to the action of a solution of a reducing agent for a periodsomewhat longer than t at necessary to efl'ect the reduction of such nickel hydrate to the first oxidation stage, and then subjecting the reduced nickel hydrate to the action of a weak alkaline solution, substantially as described.

13. The process which consists in separating the nickel hydrate and nickel of a positive. element-oi a storage battery cell of the Edison type, then subjecting said nickel by drate to the action of a boiling solution of a reducing agent, and-then subjecting the re duced nickel hydrate to the action of a weak alkaline solution, substantially as described.

This specification signed this 25th day of April, 1922. I

l'rnos. A. EnisoN. 

